The Internet world is relentlessly enthusiastic in its embrace of the latest and greatest, and this year’s new flavor has been social networking. Between MySpace, Facebook, LinkedIn, Twitter, Bebo and scores of lesser start-ups, social networking seems poised to take over the Internet. Indeed, some digerati have suggested that Facebook, by allowing developers to write mini-applications called widgets, might become the new Internet.

However, from push technology to Pets.com, the former Information Superhighway is littered with the digital corpses of the next big thing. The Internet is the early adopters’ ultimate paradise, an all-you-can-eat buffet table of novel software gadgets, and it’s dangerous to rely on the enthusiasms of the blogosphere to determine the longevity of any new Web phenomenon. But social networking may be in a class by itself—for reasons that go back long even before human memory.

A decade ago, Robin Dunbar, the British anthropologist, wrote a book called “Gossip, Grooming and the Evolution of Language.” Dunbar is one of the more influential practitioners of evolutionary psychology — looking at how the human animal behaved in our earliest ancestral environments, long before civilization, for clues about why we are the creatures we are today. It’s a fascinating book that suggests both why social networking is so popular and where it may be headed.

Dunbar begins with the premise that back when our Paleolithic ancestors were still more monkey than human, understanding one’s place in the group hierarchy was exceedingly important. Compared to other creatures, primates are unusually social animals. And thus knowledge about relationships — who’s mating with whom, who became allies, who just had a fight — was crucial for primates to maintain or advance their place in the pack. It was, Dunbar suggests, the birth of gossip. But before language evolved, how was gossip transmitted?

Dunbar speculated that the early hominids maintained and communicated their relationships via the mutual grooming behavior we still see in lower primates. Baboons and chimpanzees spend 20 percent of their time grooming one another. But grooming, Dunbar argues — besides tidying one’s fur and feeling good — was a way to establish and maintain friendships, determine the hierarchy within the tribe and signal one’s social connections to other tribe members. One might almost say that grooming was the first social networking application.

But there’s more to Dunbar’s theory. He speculates that at some point, our early ancestors’ tribes began to get too big for even the most energetic primate to get around to grooming everyone. And thus language emerged to replace grooming as a means of conveying social relationships. (It’s not clear which came first — language or the larger tribe size — but they grew in tandem.) An exchange of personal information with language was far quicker than a 20-minute grooming session, and a single individual could converse with several others at one time. So rather than the traditional anthropologic explanation that language evolved among males to coordinate hunting, Dunbar proposed that language evolved as a way to maintain and identify social relationships. And we haven’t stopped gossiping since.

Gossip’s primitive significance may explain the unending appeal of celebrity journalism. We’re still watching the behavior of the alpha males and females in our tribe, only now we identify them as Brad and Angelina (they do look awfully large on the silver screen.) In a sense, our gossip appetite is a bit like another bit of programming we inherited from our hard-living primate ancestors: the urge that tells us to consume all the food we can when it’s available. Today, of course, surrounded by fat and sugar, that dietary programming rapidly leads many of us to excess poundage. With professionally-produced gossip now as readily available as fast food, it may be only natural that we overdose on that as well.

Web-based social networking fills the same need on a personal level: it is an incredibly efficient gossip engine, with an unprecedented ability to establish the precise nature of relationships (limited profiles and privacy settings provide plenty of signals as to who’s close and who is closer). That’s an age-old attraction that’s not going away. But there’s another element of social networking that may be something altogether new.

It stems from Dunbar’s observation that, with the new tool of language, humans managed to increase their group size significantly from the 50 or so members that characterize baboon and chimpanzee groupings. But over the last 10,000 years or so, we seem to have hit another ceiling for an optimum group size in which members are reasonably in touch. That number is about 150, a figure supported by examples that range from the size of Neolithic villages to military units to corporate management theory. Organizations, of course, get bigger than that, but as they do they change character: bureaucracies, levels of authority, social stratification begin to emerge. Dunbar theorizes that this may be due to the limits of how many individuals one can converse with, based on the acoustics of speech, and still have time to take care of life’s essentials.

So the obvious question about Internet-based social networking is whether we humans are once again increasing the size of our effective groups. Is this an evolutionary shift that — while certainly not as significant as the advent of spoken language — will ultimately change the way we operate as social creatures? Will anthropologists of some distant era look back and say that this was the moment when humans once again created much larger social networks than we were able to maintain in the past? Or perhaps in the end we’ll discover that, once again, about 150 “friends” is as far as our capacities can take us.

Whether or not Dunbar’s decade-old theory about language’s origin in gossip is correct, it’s a fascinating way to think about what’s important in human communication. And it suggests that with social software, we’re for the first time arranging the Internet in a way that makes sense to the deeper inclinations of our brains. While we’re only in the very earliest days, this new twist may well be the beginning of the Internet as it is meant to be.